The small nuclear RNA's (snRNA's) of Bombyx mori tissues and cells in culture will be isolated and characterized. Major criteria for isolation of snRNA species of interest will be: (a) Immunoprecipitation with lupus erythematosus antibodies, (b) Cosedimentation with large hnRNP structures. Two-dimensional gel electrophoresis will be used to analyze the various snRNA fractions, followed by fingerprinting of individual species of interest. Possible tissue-specific variations in snRNA complexity or abundance will be investigated using these techniques. An important part of the project will be the construction of cDNA clones and genomic clones containing snRNA sequences. Restriction mapping analysis of the genomic clones will provide information about the structure of snRNA genes. Aminomethyltrioxsalen/UV crosslinking followed by hybridization to cellulose-bound genomic clone DNA will be used to isolate specific snRNA/hnRNA complexes via the snRNA sequence. HnRNA sequences isolated in this fashion will be analyzed further to determine whether they constitute a specific subset of nuclear hnRNA. A variation of this type of experiment will be directed at identifying snRNA's which interact with fibroin messenger RNA precursor molecules. Finally, the transcriptional expression of individual snRNA genes of interest will be studied in different B. mori tissues using cloned hybridization probes.